If what you meant by indexing is grabbing each word in a Word Document and creating an index of those words to find them later, the following will give you all of the words in a document. I'll let you focus on the indexing part. :)

#!/usr/bin/perl
# general use directives
use strict;
use warnings;
# project specific use directives
# this comes with the standard ActiveState
# distribution. You can also look for
# a newer version with PPM
use Win32::OLE;
my $wd;
# get the document
# use the full path
eval
{
$wd = Win32::OLE->GetObject('C:/pathto/document/foo.doc')
};
die "Unable to load document\n" if $@;
# all of the Word document data members I'm using
# are explained in the MSDN documentation of the
# external interfaces of a Word Document.
# if you have MSDN, search for "Word OLE".
# get the number of paragraphs
my $paraCount = $wd->{Paragraphs}->Count;
# set the counter
my $foo = 0;
my @words;
while ($foo++ < $paraCount)
{
push @words, split /\s/, $wd->{Paragraphs}{$foo}{Range}{Text};
}
#clean up at the end
undef $wd;